title: Distribution of protein I and regulation of its state of phosphorylation in the rabbit superior cervical ganglion.
abstract: The distribution and regulation of the state of phosphorylation of Protein I have been studied in the rabbit superior cervical sympathetic ganglion. The data indicate that the ganglion contains two pools of Protein I: a presynaptic pool that represents 60% of the total ganglion Protein I and a postsynaptic pool that represents 40% of the total ganglion Protein I. The state of phosphorylation of presynaptic Protein I, but not that of postsynaptic Protein I, is regulated by nerve impulse conduction, by dopamine, and by a high K+ concentration. Studies of the extracellular calcium requirements for Protein I phosphorylation, as well as peptide-mapping analyses of Protein I, suggest that the effects of nerve impulse conduction and of a high K+ concentration are mediated through the activation of calcium-dependent protein kinases and that the effect of dopamine is mediated through the activation of cyclic AMP-dependent protein kinase. The total amount of postsynaptic Protein I, but not that of presynaptic Protein I, is decreased by short periods of exposure to cycloheximide, a protein synthesis inhibitor. It is proposed that Protein I located in presynaptic nerve terminals plays a functional role in those terminals and that the Protein I located in cell bodies is newly synthesized and en route to nerve terminals.
mesh_terms: D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D003714:Denervation; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010643:Phenoxybenzamine / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D016704:Synapsins
chemical_list: D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D016704:Synapsins; D010643:Phenoxybenzamine; D003513:Cycloheximide; D011188:Potassium; D004298:Dopamine